The US Senate has confirmed has confirmed Kirstjen Nielsen as the next secretary of the Department of Homeland Security (DHS), after she was nominated by President Donald Trump in October.

Senators voted 62-37 on Tuesday to confirm Nielsen as head of the DHS, a post that opened after former DHS secretary John Kelly became Trump’s chief of staff earlier this year.

Nielsen, 45, was also Kelly’s deputy at the White House and his chief of staff at the DHS.

The 62-37 vote was the narrowest margin ever to approve a DHS secretary, indicating doubts about Nielson’s leadership capabilities as head of an organization that among other things, is in charge of implementing Trump’s immigration policies.

Concerns over independence

Many Democrats have been critical of Nielsen, stating she is not independent of the White House and will budge to executive demands.

One of those Democrats, Senator Maggie Hassan, said she had concerns about the new secretary’s independence.

“Throughout her confirmation process, Ms. Nielsen failed to demonstrate that she would provide the steady experienced leadership — free from political interference from the White House — that the department needs,” Hassan said.

Such concerns have not been limited to partisan circles. Frank Sharry, executive director of America's Voice Education Fund, which promotes immigrants' rights, said Trump has worked to punish immigrants and refugees, from his call to build a wall along the Mexican border to the partial travel ban to raids against immigrants.

As a key aide of Kelly, Nielsen is "one of the architects" of Trump's immigration policies, Sharry said.

He called Nielsen "a willing accomplice, helping to shape and implement this profoundly disturbing and un-American vision of our country."

The DHS has 22 sub agencies, including immigration enforcement, transportation security, disaster preparedness and response, the Secret Service, and the Coast Guard.